Several of its isotopes are radioactive, including I-131, which is used as a tracer and in thyroid disease diagnosis and therapy. Its compounds are used as antiseptics, germicides, and in the production of dyes. Silver iodide, being light sensitive, is used in photography.
Most iodine is produced from calcium iodate (Ca[IO3]2), found in Chile saltpeter. In the US, much is recovered from oil-well brine, which contains some sodium iodide (NaI).
Iodine and healthIodine is essential for the formation of the thyroid hormones, triiodothyronine (T3) and thyroxine (T4). These hormones control the rate of metabolism and growth and development.
About 100 to 300 micrograms are needed daily. A dietary shortage of iodine may lead to goiter (enlargement of the thyroid gland) or to hypothyroidism (underactivity of the thyroid gland). Iodine deficiency in the newborn can lead to cretinism.
The amount of iodine in food depends on the amount contained in animal feed and the amount in the soil; shortages occur in limestone areas. Shortages can be overcome by consuming bread or table salt fortified with iodine or iodate.
Most plants (especially seaweeds) contain traces of iodine.
Medical uses of iodineIodine is sometimes given to people who have consumed food or drink contaminated with radioactive iodine. In such cases, absorption of the body of nonradioactive iodine reduces the absorption of the radioactive iodine.
Radioactive iodine is sometimes used to damage, and thus to reduce the activity of the thyroid gland in cases of thyrotoxicosis (a toxic condition resulting from overactivity of the thyroid gland).
Iodine compounds are used as antiseptics, in radiopaque contrast media used in some X-rays procedures and in some cough remedies.
Related category INORGANIC CHEMISTRY
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